A novel power VDMOSFET (vertical double-diffused
MOSFET) structure, simulated using PISCES-II, a 2-dimensional numerical device
simulator has been described. The proposed device structure is based on the
floating islands (FLI)-diode concept and trench gate technology. Extensive
simulations were performed to understand physics of the device through various
internal electrical quantities like potential distribution, electric field,
etc. in different regions of the device both in on/off states.The simulation
results show that the new device has a low on-resistance by virtue of reduced
electric field in its drift region as well as due to the removal of parasitic
JFET region resistance. Trench gate acts as a field plate to avoid the
punch-through thus enhancing the breakdown voltage. For a 100 Volts design, an
approximate 15% increase in the breakdown voltage has been observed in the
proposed device compared to the conventional FLIMOSFET without trench gate.